The inner, or negative, rail is also known as the 'current return' rail, because electrical current needs a circuit - a return path to earth, in other words.
Source: wiktionary
Return path
Synonyms for "return path" (17 found)
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Related word relations
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More general
8 entriesMore specific
10 entriesbacktrack routehomeward pathmessage rerouteresponse routeretrace pathreturn journeyreturn to sender routereverse pathsignal redirectundelivered mail path
Collocations
10 entriesbacktrack pathdesignated routeemail return pathmail return pathnetwork return pathpath backpath back to senderretrace pathreturn path headersignal return
Inflections
4 entriesDerivations
4 entriesSample sentences
2 total sentences available.
One rail (known as the traction return rail) is not broken into [track circuit] sections as it provides the return path for the current.
Source: wiktionary